2003 Ex cab 4.8 swap to 5.3 cam an long tubes

Discussion in 'Engine & Performance' started by oldschoolchevy, Jan 10, 2017.

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  1. oldschoolchevy

    oldschoolchevy Serious!

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    Jan 27, 2007
    Troy Ohio
    Well, I've been off the forum for a good bit. But at any rate, I managed to get back in a silvy! The plans is to swap in a 5.3 in place of my 4.8. So far what I have is 2002 5.3 block cleaned up and a set of 4.8 pistons to run a high compression 5.3. I bought a Brain Tooley Truck cam stage 2 and LS6 blue springs. The heads are GM 706 heads ported and polished. Got a set of speed engineering stainless long tubes along with a Wye pipe. I'm still in the process of getting more odds and ends for it. Hopefully I'll start getting the 5.3 together here a few weeks. I plan on dyno my truck on a chassis dyno with the 4.8. Then after the 5.3 is installed and tuning dyno it again. I'll post updates and pictures of the build and install as it goes. :yuno:


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    Feb 17, 2006
    sounds like a nice setup.
    defanitly keep us updated on the build
  3. Hogg

    Hogg GMFS Member

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    Dec 25, 2005
    Ontario Canada
    Keep us informed, pretty basic swap, 4.8 out and 5.3 in. 293 cubes to 323 cubes. It will run better, but I wonder if the effort is worth the result stock for stock. The essential parts of your swap are the ported heads and the cam

    Stage 1 206/212 .525/.534 114+2
    Stage 2 212/218 .553/.553 113+2
    Stage 3 218/224 .553/.553 113+3 not in stock
    Stage 4 224/230 .553/.547 111+2 not in stock

    This would be the perfect time to slide a Trailblazer LS iNline 6 cylinder torque converter in there.
    A 2004 4.2 I-6 Trailblazer uses p/n 24228709 for US$389 including a $100core charge from Rock Auto for a Delco reman unit, or $150 for a DACCO reman from Rock Auto, that includes a $50 core charge.

    24228708 is the 2002/2003 p/n.

    Using the inline 6 torque converter goes along the same lines as guys like me who run Vortec 350 trucks who run the torque converters designed for the 4.3 V6 engines. The V6 TC's use the 4 digit alphanumeric codes DCLF or DBLF. IN gear, brakes applied 100% I can get about 2800rpm at WOT, which is much better than the stock 1700 or so rpm. Plus with the wide ratios of the 60e/65e/70e transmissions, these stock TCs actually reduce the amount of rpm drop between WOT upshifts by roughly 500-600rpm. I used to have a bad rpm drop after the 2-3 shift at the track, the truck used to feel like all acceleration would stop, but with the DCLF 4.3 V6 TC the truck kept accelerating much better than with the stocker. I got my TC for free from the wrecking yard, so it was a no brainer.
    If you cab score one for cheap, it is the perfect time for you to install it, rather than disassemble the trans later on. You will see 1/4 mile improvements of about 2-3 tenths without affecting towing ability. Just be sure to get one from an inline 6 4.2 liter engined Trailblazer ad NOT a stock TC from a Trailblazer SS with the 6.0 LS2 engine, it wont help you at all, and could make you slower.
    The I-6 4.2 engine from a TBLS is the perfect converter for tose with no experience with TC's and would like to "dip their toes" in the water before diving into a big dollar performance TC. Many aftermarket TC builders use these torque converters as peginning platforms for their less expensive more mild TC's. Circle D offers a I-6 Trailblazer TC for $400. oops sorry, they are $450 now
    Many of the high performance custom build TC are over $800 now. Circle Ds are $900 for single disks and many custom built hard parts, and $1200 for multi disks with the same custom made hardparts. You only need a multidisc TC if you are locking he TC at WOT with big power. The 4l60e/65e/70es lock their TC's at speeds above above 75mph,the 4l80e/85e trucks lock their TC's at WOT in 2nd gear and 3rd gear. This can all be adjusted via PCM/TCM recalibration.

    Here is some more info about those 4 digit torque converter codes

    more info here

    IMO Every truck on the road should have a little bit looser TC for performance increases, esp. how with every new engine family it often makes more power, but at the expense of extended rev ranges.
    here's a sample
    GM RWD Torque Converters

    Starting 1980-up, GM used a 4-digit ID sticker located on the converter body to help identify it. Below is a guide to help decipher it's meaning.

    1st Digit (application trans)

    • B -- THM250C, THM350C
    • C -- 200C, 2004R, Pre-1984 1/2: 325-4L & 700r4
    • D -- 1984 1/2-up 700r4, 4L60, 4L60-E
    2nd Digit (approx stall, depends on engine)

    • B -- 2025 rpm
    • C -- 2075 rpm
    • E -- 1654 rpm
    • F -- 1611 rpm
    • G -- 1397 rpm
    • H -- 1397 rpm
    • K -- 1211 rpm
    • L -- 1654 rpm
    3rd Digit (Clutch Assembly)

    • 3 -- Poppet Valve
    • 7 -- Poppet Valve
    • 9 -- Poppet Valve
    • A -- Red (pre-96)
    • A -- Carbon (96-up)
    • B -- Static Open
    • G -- Carbon Fiber
    • H -- Red (pre-96)
    • H -- Carbon (96-97)
    • H -- Woven Graphite (98-up)
    • L -- Carbon Fiber
    • N -- Woven Graphite
    • P -- Woven Graphite
    4th Digit (Body Mounting)

    • C -- 3 round lugs, gas engine
    • D -- 3 round lugs, diesel engine
    • E -- 6 round lugs, gas or diesel
    • F -- 3 square pads, gas or diesel
    • G -- 3 square pads, gas or diesel
    If there is no ID tag, there might be a number or letter stamped between the dimples of the impeller on the converter body.

    • 4 -- 1211 stall
    • 5 -- Medium or high stall (depends on stator)
    • 6 -- 1397 stall
    • 7 -- 1654 stall
    • C -- 2075 stall
    • H -- 1397 stall
    • K -- 1211 stall
    • L -- 1654 stall
    And this is the info from "The Herd" which is the 94-96 Impala SS guys, this where I learned of the 4.3 TC's. Exact same principle as the newer 4l60e/65e/70e transmissions.

    I have a 2007 Trailblazer LS with the 293hp 4.2 liter engine. For a stone stock engine, once the tach gets over 3500rpm and esp from 5000-6200rpm does it ever pull well.

    Let us know how it goes and what your results are. I'm always excited about guys doing builds. Its so fun to have a truck, then get some parts, esp speed parts and finding out how they all work when they are assembled. Your truck will run with the stock TC, but like I said, even a stock truck is quicker with the V6/I-6 TC's installed behind the V8's.
    Good luck my friend

  4. oldschoolchevy

    oldschoolchevy Serious!

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    Jan 27, 2007
    Troy Ohio
    Man thats some great info! Yeah reason for the 5.3 stock swap moreless is it was free and Im still driving the truck. So when I get the motor together I can just swap them out and be off! Im going to looking to the converter setup though.

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